2408.03403
ON THE COMPLEXITY OF SUBSHIFTS AND INFINITE WORDS
Be’eri Greenfeld, Carlos Gustavo Moreira, Efim Zelmanov
correctmedium confidence
- Category
- Not specified
- Journal tier
- Top Field-Leading
- Processed
- Sep 28, 2025, 12:56 AM
- arXiv Links
- Abstract ↗PDF ↗
Audit review
The paper proves Theorem 1.1: for any non-decreasing f with f(n) ≥ n+1 and f(2n) ≤ f(n)^2 there exists a recurrent infinite word w with p_w ∼ f, via an explicit multiscale marker construction with “balanced” indices and three growth regimes, and upgrades bounds along a bounded-ratio subsequence using a monotonicity lemma. This exactly matches the model’s outline, which restates the construction (dictionaries/markers, balanced stages, three regimes), the recurrence argument, and the Lemma 2.2 subsequence-to-all-n step. Minor notational simplifications in the model (e.g., using |W_k| instead of n_k s_k) don’t affect correctness. See Theorem 1.1 and its proof sketch, the balanced-index framework and cases, the recurrence Lemma 4.1, the balanced-index bounds (Corollary 4.3), and the conclusion p_X ∼ f via Lemma 4.4 and Lemma 2.2 in the paper .
Referee report (LaTeX)
\textbf{Recommendation:} minor revisions \textbf{Journal Tier:} top field-leading \textbf{Justification:} This work delivers a sharp, long-sought characterization of complexity functions of subshifts/infinite words up to asymptotic equivalence via an explicit, robust construction. The recurrence mechanism and complexity estimates are clear and compelling, and the subsequence upgrade completes the argument cleanly. Minor presentation tweaks (notation and emphasis on why n\_k s\_k governs p(n\_k)) would further enhance readability.